1. FIELD OF THE INVENTION
This invention relates generally to reamers, and more particularly to a chamfering reamer for threading machines which chamfers the interior and/or exterior of the threaded end of pipe or conduit and has a trip shoulder for activating a chaser holder of the threading head upon completion of the threading and chamfering operation to release the chamfered piece.
2. BRIEF DESCRIPTION OF THE PRIOR ART
Chamfering reamers are secured by an adjustable draw bar in the threading head member of a threading machine and chamfer the ends of a pipe or conduit to remove the burr from the inside or outside diameter of the pipe or conduit after it has been threaded.
Some reamers, such as those manufactured by Teledyne Landis Machine of Waynesboro, Pennsylvania are designed to chamfer the inside and outside diameter of the pipe or conduit simultaneously. This type of reamer has a fluted body forming longitudinal wings which have an integral rearwardly extending, flat-bottom, generally V-shaped groove in the front portion of each wing. The converging inner sides of the V-groove chamfer the material and the flat-bottom of the V-groove serves as a stop bar at the end of the threading operation by forceably contacting the end of the pipe or conduit sufficient to activate a trip release within the threading machine to release the chamfered piece.
Prior art reamers of this type frequently become worn and require replacement or re-grinding of the cutting surfaces. The suggested method of resharpening or grinding is to grind on the flat side of each wing. This seriously impairs the useful life of the reamer because it reduces the cross section of the wing and changes the geometry of the cutting edges. The thinner reworked wings are often broken because the outer side wall of the flat bottom V-shape is thin and has a vulnerable stress point. The flat bottom tripping surface of the V-groove does not provide a desirable relief angle, and results in chip buildup which often causes damage to the first threads or even tearing off the end of the pipe. The flat bottom tripping surface of the V-groove is perpendicular to the longitudinal axis, and will also often gouge or damage the end of the pipe or conduit when forceable contact is made during the tripping sequence.
Another common problem with chamfering reamers is the down-time or loss of production caused by the necessity of frequent replacement and re-setting of a new reamer.
Other reamers are known in the art. There are several patents which disclose reamers and cutting tools of various configuration.
Press, U.S. Pat. No. 4,016,614 discloses a combination screwdriver and reamer having a blade with a edge for manually deburring the internal diameter of cut conduit or pipe.
Williams, III et al, U.S. Pat. No. 4,682,917 discloses a spade bit which improves the cutting rate and has radial flutes on the lateral shoulders with spurs at the outer ends of the shoulders.
Heule, U.S. Pat. No. 4,165,201 discloses a deburring tool comprising a tool holder with a plurality of knives having cutting edges which contact the bore edge by advancing in a longitudinal direction of the tool holder. The reactive force against one or more of the knives automatically positions the remaining knives longitudinally.
Jackley et al, U.S. Pat. No. 4,134,704 discloses a tapered blade type rotary hole cutter. The blade is generally flat, being tapered in the width direction for applying the taper to the hole, and being tapered in the thickness direction so that the longitudinal cutting edge along its length will lead the cutting edges proximate the point and thereby minimize point drift.
Simonffy, U.S. Pat. No. 3,706,504 discloses a spiral drill having a working end with a plurality of cutting faces, all of which are substantially parallel to the longitudinal axis of the tool and have cutting edges along the forward ends of the faces. A clearance surface is rearwardly disposed at an angle of approximately 45.degree. from each of the cutting faces.
Stillwagon, Jr., U.S. Pat. No. 3,207,196 discloses a boring tool for countersinking recesses in wallboard and driving screws. The tool has four equally spaced wings at the forward end separated by flutes and a countersinking portion extending outwardly and rearwardly from the front for forming screw head recesses in the wallboard. The forward end of the wings are configured to fit a screw head slot and drive the screw.
The present invention is distinguished over the prior art in general, and these patents in particular by a chamfering reamer for reaming the inside diameter of pipe or conduit which has generally cylindrical body with a truncated conical forward end to be received within the inside diameter of a pipe or conduit and a rearward end adapted to be secured in a chaser holder of a threading machine and a plurality of longitudinal flutes extending rearwardly from the forward end defining a plurality of circumferentially spaced longitudinal wings. Each wing has a conical reaming portion to ream the interior diameter at the end of the pipe or conduit and a conical trip shoulder extending from the conical reaming portion to the outer surface of each wing to activate the chaser holder to release the chamfered piece and provide clearance between the end surface of the pipe or conduit being reamed. Another embodiment for simultaneously reaming interior and exterior diameters has a body with the above described features which removably receives a hollow cylindrical sleeve having forwardly extending projections in circumferential alignment with the wings. Each projection has a reaming surface extending inward in opposed relation to the conical reaming portion of the wing to form a plurality of rearwardly extending generally V-shaped, angular bottom grooves which simultaneously ream the interior and exterior diameters at the end of the pipe or conduit. Another embodiment has replaceable inserts on the leading edge of the wing portions.